28 



THE PRACTICAL FISHERMAN. 



Cobbold (Synopsis of the Distomidae) that of 344 species of " fluke " (or 

 Trematoda) no less than 126 belonged to fishes. The same author also 

 adds that this species of entozoa are " particularly plentiful in the stickle- 

 back, minnow, tench, perch, pope, trout, salmon, and still more abundant 

 in pike, barbel, bream, eel, &c." 



One of the most interesting of these peculiar creatures belonging to 

 the above genus is the Gyrodactylus elegans, which I have more than 

 once extracted from the gills of the bream. I read that Siebold and 

 Creplin both found members of the same family attached to the fins, but I 

 think it more properly is an internal parasite, and have so considered it. 

 In this case an almost completely developed embryo could be perceived 

 contained in the abdominal cavity. 



Of the order of Nematoda, or round worms, I have repeatedly met 

 members of the family Anguillulidce in nearly all fresh- water fish. Of 

 course, I am aware that some of the species, such as the '*' vinegar " 

 eel, are non-parasitic, but others are not so, which is proved by my 

 detection of them in the digestive system of the eel. It is an. exceed- 

 ingly minute worm, not often of a greater length than the tenth of an 

 inch. Its tenacity of life is very remarkable. The observations of 

 Needham, Bauer, and Dujardin have shown that the animal is capable of 

 revivification even after a period of desiccation extending over five years. 



The "thorn-headed" worms are particularly numerous in fish, 

 especially in roach. I have found the large intestine of this fish 

 completely studded with the Echinoshynchus anthuris, whilst a trout 

 caught in June, 1877, exhibited a great many of a kindred species, the 

 Echinoshynchus proteus. Its head is cone-shaped, studded with incredibly 

 sharp thorns, set barb wise. I am inclined to attribute the wasting or 

 atrophy to which the fish is subject to the presence of members of the 

 Echinoshynchidce. 



I have thus briefly and scantily touched upon a few of the more minute 

 and curious parasites which infest fish to my own knowledge. I now 

 come to notice the large and important order of Cestoda, or " tapeworm,' ' 

 specimens of which I have more frequently than any other parasite taken 

 from the intestines of our fresh-water fish. In order to obtain a correct 

 idea of their nature as regards fish, it must be borne in mind that, as a 

 general fact, the tapeworms found in fish are immature or larval cestodes, 

 waiting to find themselves inside the heron, or plover, gull, diver, duck, 

 or some such water bird before developing to maturity. Therefore, such 

 worms usually display considerable difference in structure to those 

 inhabiting mammals, " being commonly furnished," says Dr. Cobbold, 

 "with special tentacular hooks, appendages employed as supplementary 

 organs of boring and anchorage." There are variations from this, how- 



